Brent Christensen is living proof of that playing with ice isn’t just for little ones. Ice Castles began as a father’s imaginative backyard project for his children — Christensen built an ice rink, a 20-foot ice slide and a tower at his home in Utah. Now, Christensen is thinking bigger. He and his team “grow” icicles daily, putting them together to form astonishing, dreamlike sculptures. The formations are made of millions of pounds of ice and include looming towers, caves and tunnels that visitors can pass through. Each structure changes day to day as icicles melt and new ones are added.

This year, Ice Castles have opened in Breckenridge, Colo.; Lincoln, N.H.; and Midway, Utah. To make the most of your visit, explore a castle during the day, then get your hand stamped and return for free at night, when the castles are illuminated from within. Admission ranges from $5 to $10, depending the day of the week and the age of the guest. Kids under three get in for free. www.icecastles.com